Effects of yeast and algal diets on the growth and biochemical composition of the rotifer Brachionus plicatilis (Müller) in culture

Abstract. Growth rates and fecundity of Brachionus plicatilis fed baker's yeast, a diatom, and three different flagellates, were monitored during a 15-day feeding trial. Identical growing conditions and equivalent food levels for the different diets were maintained during rotifer culture. The highest growth rate and mean fecundity were exhibited by rotifers fed Chlorella saccharophila , followed in decreasing order by those fed Isochrysis galbana (T-iso), Tetraselmis suecica, Saccharomyces cerevisiae and Thalassiosira pseudonana . Significant differences in contents of neutral lipids, polar lipids, sugars, glycogen, protein, ash and corresponding energy reserves in the resultant five groups of rotifers were diet dependent. Total available energy, about 15 kJ/g in rotifers fed S. cerevisiae and I. galbana (T-iso) was significantly different from the 14kJ/g in rotifers fed T. suecica and C saccharophila, and in turn from the 13kJ/g in rotifers fed T. pseudonana .     

Evaluation of the air sac volume of penguins with respiratory diseases using computed tomography

Captive penguins with respiratory diseases exhibit advanced pathological conditions upon the appearance of clinical signs. Therefore, the successful treatment of respiratory diseases remains difficult after the onset of clinical signs, leading to high mortality rates. In this study, we measured air sac volume using computed tomography (CT) to evaluate the respiratory condition of penguins. In a regular quarterly health checkup, blood samples were collected from 45 penguins housed at an aquarium in Hokkaido, Japan. A total of 12 penguins with abnormal blood parameters underwent CT. The air sac volumes were calculated in three-dimensional CT, and the scatter plots of the air sac volumes and body weights were analyzed. No correlation was found between the air sac volume and body weight in both the gentoo and king penguins. Two gentoo penguins with infiltration and one king penguin with multiple nodules on CT were tentatively diagnosed with aspergillosis and treated with oral administration of itraconazole. Follow-up CT examination was performed until the outcome: healed or died. The mean air sac volumes of the two gentoo penguins, which recovered after treatment, increased from 273.9 and 329.0 cm³ before healing to 449.0 and 424.6 cm³ after healing, respectively. Meanwhile, the air sac volume of the king penguin, which subsequently died, decreased from 1,556.9 to 920.6 cm³ despite treatment. Changes of the air sac volume in the same individual could be useful for evaluating the respiratory condition of penguins.     

Improving the accuracy of estimating blood calcium concentration in Holstein cows using electrocardiographic variables

We previously reported the possibility of using the electrocardiogram variable to estimate blood calcium (Ca) concentration in dairy cows based on the strong positive correlation between the blood Ca concentration and the inverse of the corrected ST peak interval (STc⁻¹). To improve the accuracy of the estimation of blood Ca concentration, we investigated the relationship between blood Ca concentration and STc⁻¹ for each postpartum day and available variables other than STc⁻¹. We measured multiple variables (milk yield, calving number, age, body temperature, etc.), including serum total Ca concentration (tCa), blood ionized Ca concentration (iCa) and STc⁻¹ in 462 Holstein cows on days 0, 1, 2, 3, 5, and 7 postpartum. A very high correlation was observed between iCa and tCa. The association between tCa and STc⁻¹ for each postpartum day had a high coefficient of determination of 0.61–0.79 postpartum 0–2 days but decreased after the third day. In the investigation using the data from postpartum days 0–2, STc⁻¹, heart rate interval, calving number, and age were highly correlated with tCa. In addition, a multiple regression equation was obtained with tCa as the objective variable and STc⁻¹ and calving number as explanatory variables. The estimation accuracy was improved as compared with the simple regression equation using only STc⁻¹ as the explanatory variable. This multiple regression equation was used for 11 cows suspected of having hypocalcemia, and it was able to correctly detect cows requiring early treatment, except for one cow.     

Effect of lodging on the level of mycotoxins in wheat,barley, and rice infected with the <Emphasis Type="Italic">Fusarium graminearum</Emphasis> species complex

Lodging is one possible risk factor that leads to increased cereal mycotoxin contamination, but few reports have been published on the subject. We examined the effects of lodging on the level of deoxynivalenol (DON) and nivalenol (NIV) contamination in wheat, barley, and rice infected with the Fusarium graminearum species complex. Case-control and intervention studies were applied to test the hypothesis that lodging increases the level of mycotoxin contamination. A total of 66 grain samples were collected from each field in 12 Japanese prefectures from 2002 to 2006. Each sample set consisted of grains from lodged and nonlodged plants. The concentration of DON + NIV in lodged plants was significantly higher than in nonlodged plants. All samples of wheat and barley were contaminated with DON and NIV; however, most of the lodged rice samples were contaminated only with NIV. In intervention trials to investigate the effects of lodging duration, a small area of wheat inoculated with the pathogen was completely lodged by trampling. Even with 5 days of lodging, the levels of DON + NIV in wheat grain at harvest increased by 27–51% compared to nonlodged control plots. For rice, half of each plot area was completely lodged by trampling 20 days before harvest. The level of NIV in lodged rice grain was significantly higher than that in nonlodged rice at optimum and delayed harvests, because lodging significantly increased the level of Fusarium mycotoxins in the three crops. Thus, practices (e.g., rational use of fertilizers) to avoid lodging should reduce the risk of mycotoxin contamination. This is the first epidemiological study on the effect of lodging on mycotoxin production by the F. graminearum species complex in wheat, barley, and rice.     

The enhancement of Th1 immune response by anti-PD-L1 antibody in cattle infected with Mycobacterium avium subsp. paratuberculosis

Johne’s disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic enteritis of ruminants. Previous studies have shown that programmed death-ligand 1 (PD-L1) is associated with the disease progression, and PD-L1 blockade activates MAP-specific Th1 responses in vitro. Here, we performed anti-PD-L1 antibody administration using 2 MAP-infected cattle at the late subclinical stage of infection. After administration, bacterial shedding was reduced or maintained at a low level. Additionally, MAP-specific Th1 cytokine production was upregulated, and CD69 expression was increased in T cells. Collectively, the treatment has a potential as a novel control method against Johne’s disease.     

Availability of culture filtrate protein-10 (CFP-10) secreted from Mycobacterium pseudoshottsii for mycobacteriosis diagnosis in ginbuna crucian carp Carrasius auratus langsdorfii

Mycobacteriosis in cultured fish is a challenge for the aquaculture industry worldwide. Treatment by chemical administration is difficult and no effective vaccine has been developed. Therefore, detection and isolation by early diagnosis are important for prevention of the spread of the disease. In mammals, interferon gamma release assays have been established for detection of tuberculosis; these tests are based on the delayed-type hypersensitivity (DTH) response against culture filtrate protein-10 (CFP-10) and the 6-kDa early secreted antigen target (ESAT-6) of Mycobacterium tuberculosis. On the other hand, little is known about the fish immune response against the ESAT-6 and CFP-10 proteins of mycobacteria, although these responses should find application in the diagnosis of mycobacteriosis in fish. In the present study, we identified ESAT-6 and CFP-10 from Mycobacterium pseudoshottsii and cloned the corresponding genes. Intraperitoneal injection of the corresponding DNA plasmid constructs in ginbuna crucian carp yielded increased expression of the fish interferon-γ1-1-encoding gene (IFN-γ1-1). In contrast, IFN-γ1-1 expression accompanied by DTH response was observed only in the CFP-10-DNA plasmid-injected fish. Furthermore, fish that had been prophylactically injected with CFP-10-DNA plasmid exhibited increased survival of M. pseudoshottsii infection. Taken together, these results suggested that CFP-10 may facilitate diagnosis of mycobacteriosis.     

Growth and spawning of hatchery-reared Chinese white prawn Penaeus (Fenneropenaeus) chinensis released in the Ariake Sea, Japan

SUMMARY: Growth and reproduction of hatchery-reared Chinese white prawn Penaeus chinensis released in the Ariake Sea, Japan, were examined. Chinese white prawn grew rapidly, reaching a body length of 154 mm in males and 198 mm in females by November (219–229 days after hatching). Maximum body length of sampled individuals was 164 mm in males and 223 mm in females. Growth curve of the Chinese white prawn was fitted to the Pitcher and MacDonald's formula, L_t = 155.0{1 − e ^{2.925sin[2π(t − 16.151)/365] − 0.0623( t − 10.712)}} for males and the logistic curve, L_t = 200.3/[1 + e ^{(1.985–0.034 t )}] for females (where L_t is the body length t days after release and t is the number of days after release). Females reached sexual maturity in late February and spawning occurred until April. Minimum size at ripe and spawned stages was 189 mm and 193 mm body length, respectively.     

A membrane-anchored protein kinase involved in Brassica self-incompatibility signaling

Self-incompatibility (SI) response in Brassica is initiated by haplotype-specific interactions between the pollen-borne ligand S locus protein 11/SCR and its stigmatic S receptor kinase, SRK. This binding induces autophosphorylation of SRK, which is then thought to trigger a signaling cascade that leads to self-pollen rejection. A recessive mutation of the modifier (m) gene eliminates the SI response in stigma. Positional cloning of M has revealed that it encodes a membrane-anchored cytoplasmic serine/threonine protein kinase, designated M locus protein kinase (MLPK). Transient expression of MLPK restores the ability of mm papilla cells to reject self-pollen, suggesting that MLPK is a positive mediator of Brassica SI signaling.